1. Field of the Invention
The present invention pertains to the field of semiconductor integrated circuits. More specifically, the present invention relates to the transferring of integrated circuit devices into and/or out of a plurality of sockets, as may occur during the burn-in process, for example.
2. Description of the Related Art
Integrated circuit devices often must undergo a bum-in process, whereby the devices are operated under accelerated aging conditions to stabilize their circuitry and to detect premature failures. Such accelerated aging conditions may include an elevated temperature (the devices may be baked in an oven), elevated voltage and/or elevated humidity. To start the burn-in process, the devices to be burned in must be removed from a tray or tube onto or in which the devices were placed after manufacturing and loaded onto a burn in board. The burn in board may include a plurality of sockets, which are receptacles that mechanically hold the devices in place and electrically couple the device to be burned to the testing circuitry. In the case of Zero Insertion Force (xe2x80x9cZIFxe2x80x9d) sockets, the top portion of the sockets (also called the xe2x80x9clidxe2x80x9d of the socket) must be pushed down in order to retract the contacts of the socket. The leads of the device may then drop down into corresponding holes in the socket, whereupon the socket lid may be released, causing the socket contacts to come into contact with and bear down on the device leads, thereby mechanically holding and electrically coupling the device to the socket.
Automated loaders exist to load and unload integrated circuit devices into and out of burn in board. Such devices rely upon a so-called preciser, which compensates for any misalignment between the tray on which the devices rest prior to loading and the burn in board sockets. A suction device on the automatic loader picks up the devices from the tray and places them on the preciser. The devices must then be picked up from the preciser and placed within the sockets of the burn in board. The unloading operation follows the opposite sequence: the devices are picked up from the sockets and placed on the preciser, whereupon they are again picked up and placed back upon the tray for later testing. Each of these motions may be considered to be an insertion and automated loaders carry out the equivalent of four insertions. Each such insertion increases the risk that the leads of the device will be bent, which decreases the yield of the overall process. As automated loaders are complex and costly devices (typically costing on the order of several hundreds of thousands of dollars), their suitability must be carefully evaluated, not only in terms of purchasing and, maintenance costs, but also in terms of the attendant risk of damaging the leads of the integrated circuit devices to be burned in.
One alternative to such automated loaders is to carry out the device loading and unloading process manually. However, such loading can become tiring for the worker, who must manipulate small outline packages (such as Thin Small Outline Package xe2x80x9cTSOPxe2x80x9d, for example) and corresponding sockets with their fingers without damaging the leads of the devices to be inserted in the sockets. Indeed, the worker must push down the lid of the ZIF socket to retract the socket contacts while simultaneously aligning the device with and pushing the device into the socket. Understandably, damaged leads are a relatively common occurrence when the devices are transferred into and/or out of sockets in this manner.
What are needed, therefore, are devices and methods for transferring of integrated circuit devices into and/or out of a plurality of sockets that are inexpensive and that ease the strain on the workers"" fingers as he or she loads and/or unloads the devices from the sockets. Also needed are devices and methods that increase the speed at which integrated circuit devices may be loaded and/or unloaded from a plurality of sockets.
An object of the present invention, therefore, is to provide improved devices and methods for loading and/or unloading integrated circuit devices from a plurality of sockets. In particular, the objects of the present invention include providing devices and methods to transfer integrated circuit devices to and from mating sockets that are inexpensive to implement and maintain, that are less damaging to the leads of the devices and that exhibit an increased yield.
In accordance with the above-described objects and those that will be mentioned and will become apparent below, an apparatus for transferring of integrated circuit devices into and/or out of a plurality of sockets, according to an embodiment of the present invention, includes at least one guide rod; a presser housing slidingly coupled to the guide rod; a socket presser block movably coupled to the presser housing, and a handle assembly. The presser block defines a matrix of cutouts and ribs and is configured to assume a first position in which the presser housing is slideable on the guide rod and a second position in which the matrix of cutouts is aligned with corresponding underlying sockets mounted to a board and in which at least some of the ribs push on the underlying sockets to retract contacts thereof to allow the devices to be transferred into and/or out of the underlying sockets through the cutouts. The handle assembly is mechanically coupled to the presser block and is configured to selectively assume an unlocked position that places the presser block in the first position and a locked position that places the presser block in the second position.
According to further embodiments, the apparatus further includes a presser guide post, the presser guide post constraining a motion of the presser block as it transitions between the first and second positions. At least one return spring may be disposed between the presser housing and the presser block, the return spring biasing the presser block away from the presser housing. A guide rod supporting structure may also be provided, the structure defining an indentation therein and wherein the presser housing includes a bearing, the bearing being configured to roll on the base as the presser housing is slid on the guide rod, the bearing perceptively dropping into the indentation when the matrix of cutouts defined in the presser block is aligned with the underlying sockets. Each of the underlying sockets may include a first side and a second side opposite the first side and at least one of the ribs may be configured to simultaneously push on the first side of a first socket and on the second side of a second socket disposed immediately adjacent to the first socket. The handle assembly may include a bearing assembly that bears on the presser block as the handle assembly is transitioned between the unlocked and the locked position. The handle assembly may include independently movable first and second handles pivotally coupled to the presser block, the first and second handles being disposed on respective sides of the presser block that are parallel to the at least one guide rod. The presser housing and the presser block may be dimensioned and oriented such that a length thereof extends at least across a width of the board.
According to another embodiment thereof, the present invention is a method of transferring of integrated circuit devices into and/or out of a plurality of sockets, including steps of disposing a socket presser block across at least some of the plurality of sockets, the presser block defining a matrix of cutouts and ribs and being configured to assume a first position in which the presser block is movable and a second position in which the matrix of cutouts is adapted to align with corresponding underlying sockets mounted to a board and in which at least some of the ribs are adapted to push on the underlying sockets to retract contacts thereof to allow the devices to be transferred into and/or out of the underlying sockets; a first placing step to place the presser block in the first position and moving the presser block so the sockets are aligned with the cutouts, and a second placing step to place the presser block in the second position and manually transferring the devices into and/or out of the sockets underlying the cutouts.
The first and second placing steps may include steps of switching a position of a handle assembly that is mechanically coupled to the presser block, the handle assembly being configured to selectively assume an unlocked position that places the presser block in the first position and a locked position that places the presser block in the second position. The transferring step may include a step of manipulating the devices with a vacuum pen. The presser block may be movably coupled to a presser housing that may be configured to slide against a guide rod and the moving step may include a step of sliding the presser housing until the cutouts are aligned with the underlying sockets. The guide rod may be supported by a guide rod supporting structure, the stricture defining an indentation therein. The presser housing may include a bearing that is configured to roll on the base as the presser housing is slid on the guide rod, and wherein the moving step is carried out until an operator perceives the bearing dropping into the indentation, which indicates that the matrix of cutouts defined in the presser block is aligned with the underlying sockets.
The foregoing and other features of the invention are described in detail below and set forth in the appended claims.